The actor ~zeno has an "/etc/resolv.conf" file, with a nameserver entry of the Oracle of Names.

Because the merciful goddess DHCP has given Tantalus a constantly changing address as a hiding place, Zeno the Torturer needs the service of the Oracle of Names to discover the current address of his victim.

Act I - Erasure of the Table of ARP and Placing the Tap

In one xterm on host 'zeno', delete the ARP (Address Resolution Protocol) table and run tcpdump to spy on on the TCP/IP traffic.
The reason for this deletion will become clear at the end of this 'tragedy' .

-s 512 : decode not only the header but also 512 bytes of data
-e : show the MAC, or linklevel, addresses
-n : show the numerical IP addresses, don't use DNS to resolve to symbolic names
-i fxp0 : specify the interface 'fxp0'

If 'zeno' would have had previous TCP/IP communciation with 'tantalus' and nameserver 'parmenides', we wouldn't
have seen the ARP traffic. Only if a host cannot find an IP<->MAC address mapping in the ARP table, an ARP request has to be done.

A tcpdump of another ping from zeno to tantalus, with a filled arp table, shows no arp traffic

Each BSD OS is equipped with all the tools to diagnose a TCP/IP problem. A program like 'ifconfig' allows you to check the configuration of your NIC. And 'tcpdump' shows exactly the exchange of packets.

We have seen what in a well configured network should happen during a "ping -c2 hostname'.

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You don't need to be a genius to debug a pf.conf firewall ruleset, you just need the guts to run tcpdump